Scientists say the size of the threatened shelf is about 5,571 square miles.
"We are in for a lot more events like this," said professor Ted Scambos, a glaciologist at the National Snow and Ice Data Center at the University of Colorado at Boulder.
Scambos alerted the British Antarctic Survey after he noticed part of the Wilkins ice shelf disintegrating on February 28, when he was looking at NASA satellite images.
Late February marks the end of summer at the South Pole and is the time when such events are most likely, he said.
"The amazing thing was, we saw it within hours of it beginning, in between the morning and the afternoon pictures of that day," Scambos said of the large chunk that broke away on February 28.
The Wilkins ice shelf lost about 6 percent of its surface a decade ago, the British Antarctic Survey said in a statement on its Web site. (...more)